1. Field of the Invention
This invention relates to an optical disc apparatus of CLV (Constant Linear Velocity) type which reproduces signals from an optical disc rotated with a constant linear velocity.
2. Description of the Related Art
Heretofore, there has been an optical disc apparatus of CLV (Constant Linear Velocity) system which reproduces data, in which a linear velocity at the data reproducing position is held constant, for the inner and the outer peripheries of the disc. In the optical disc apparatus, to read a data of the disc, at first, an optical pick-up is moved to the vicinity of the data reading position of the disc by rough seeking. Next, a laser light is emitted from the optical pick-up toward the disc, and a signal which depends on the reflected light is detected. Subsequently, a clock which has been synchronized with the reproduced signal is generated in a phase locked loop (PLL), data recording position (address) information is read, and more detailed precise seeking is started.
More specifically, when the disc has been rotation-controlled and the linear velocity on the signal detecting position has reached to the predetermined linear velocity, the frequency of the detected signal reaches into the range of frequency pulling of PLL (hereinafter, referred as the "capture range"), and pulling of the PLL into the detected signal is started.
In the case where the linear velocity of the signal detecting position of the disc is controlled by rotation controlling, the time for the linear velocity to reach the predetermined linear velocity at which PLL can be pulled into the detected signal occasionally takes longer than the time required to reach the optical pick-up to the vicinity of the predetermined recording position area of the disc. In this case, even if the optical pick-up has reached the predetermined recording area on the disc, the PLL can not be pulled into the detected signal, until the linear velocity of the signal detecting position reaches the predetermined linear velocity. Therefore, there has been the problem that time is taken from the moment at which the optical pick-up has reached the predetermined recording area of the disc until the moment at which the precision seeking is started.